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• ffmpeg record audio from Xvfb on Centos

  25 mai 2017, par boygiandi

  I’m trying to record audio from Xvfb. And I have some problems :

  1. What’s the different between alsa and pulse. I get confuse
  2. Server Centos have no soud card :

  arecord -l

  arecord : device_list:268 : no soundcards found...

  3. I may have many Xvfb process, how to record video and audio from specific Xvfb process. I checked this https://trac.ffmpeg.org/wiki/Capture/ALSA#Recordaudiofromanapplication but still don’t understand how it works.

  ffmpeg -f alsa -ac 2 -i hw:0,0 -acodec pcm_s16le output.wav

  I seen many command like this, but I don’t know how to get hw:0,0 ( id of sound card ? )

  Please help. Thanks

• ffmpeg on android : playing MPEG2 TS udp multicast stream

  27 août 2013, par user1513822

  I want to make android media player using ffmpeg.
  (catch MPEG2 TS multicast stream via WIFI network and decode it)
  I checked followings :

  • My iptime AP supports WIFI multicast protocol.
    (send multicast stream in wired PC, and wifi connected PC can receive it)
  • My Android phone can receive multicast stream via WIFI.
    I coded NDK socket programming which is join udp multicast group and receive packets
    (I added multicast access grant to AndroidManifest.xml)
  • FFMPEG library is ported to android and it can play local media file.

  But when I try to open network stream using FFMPEG library, avformat_open_input() function returns fail.

  gFormatCtx = avformat_alloc_context();
  
  av_register_all(); 
  
  avcodec_register_all(); 
  
  avformat_network_init(); 
  
  if(avformat_open_input(&gFormatCtx,"udp://@239.100.100.100:4000",NULL,NULL) != 0)
  
      return -2;

  this code always return "-2".
  If I use "av_dict_set()" api, which option should I use ?

  av_dict_set(&options, "udp_multicast", "mpegtsraw", 0);

  please let me know what should I check for avformat_open_input error ?

  thanks.

• Missing functions in new version of FFmpeg

  25 avril 2013, par Asik

  I am upgrading a wrapper around ffmpeg to the most recent version of the library. Some functions have been renamed or replaced. For the most part I've been able to found equivalents easily, but the following two are giving me trouble :

  av_abort_set_callback
  
  av_abort_default_callback

  I could not find these functions by searching online, so what happened to them and what should they be replaced with now ?

  Here is a copy of the header file "abort.h" where they were located :

  /* 
  
   * This file is part of FFmpeg. 
  
   * 
  
   * FFmpeg is free software; you can redistribute it and/or 
  
   * modify it under the terms of the GNU Lesser General Public 
  
   * License as published by the Free Software Foundation; either 
  
   * version 2.1 of the License, or (at your option) any later version. 
  
   * 
  
   * FFmpeg is distributed in the hope that it will be useful, 
  
   * but WITHOUT ANY WARRANTY; without even the implied warranty of 
  
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU 
  
   * Lesser General Public License for more details. 
  
   * 
  
   * You should have received a copy of the GNU Lesser General Public 
  
   * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 
  
   */
  
  
  
  #ifndef AVUTIL_ABORT_H
  
  #define AVUTIL_ABORT_H
  
  
  
  /** 
  
   * Causes abnormal program termination. By default, av_abort_callback calls 
  
   * abort() from the stdlib. This behavior can be altered by setting a 
  
   * different av_abort callback function. 
  
   */
  
  
  
  void av_abort_internal(void);
  
  void av_abort_set_callback(void (*)(void));
  
  void av_abort_default_callback(void);
  
  
  
  #define av_abort()    do { av_log(NULL, AV_LOG_ERROR, "Abort at %s:%d\n", __FILE__, __LINE__); av_abort_internal(); } while(0)
  
  
  
  #endif /* AVUTIL_ABORT_H */